Vacuum breaker



FIG. 1 is a perspective view of a vacuum breaker, showing my new design;

FIG. 2 is a side elevation view thereof;

FIG. 3 is a front view thereof; and,

FIG. 4 is a top plan view thereof.

The broken lines shown in FIGS. 1-4 are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a vacuum breaker, as shown and described. 